In view of the wide variety of products that are sold for being dispensed from containers, particularly containers with round necks which define the dispensing portal, numerous constructions have evolved for container stoppers or closure means for the portals. Generally, products such as vinegar, vegetable oils, laboratory liquids, detergents, honey, condiments, spices, alcoholic beverages, and the like, impose similar requirements on the type and construction of the closure means used for containers for these products. However, wine sold in bottles represents the most demanding product for bottle closure means, due to the numerous and burdensome requirements placed upon the closure means used for wine bottles. In view of these demands, most wine bottle closures or stoppers have been produced from a natural material known as “cork”.
Although synthetic materials have been proposed for use as wine bottle stoppers or closures, such products have been unable to satisfy all of the stringent requirements. As a result, cork has remained the dominant material for wine closures, in spite of the numerous inherent problems that exist with cork.
Cork represents the bark of a particular variety of cork oak, quercus suber, a tree of the oak family characteristic of western Mediterranean countries, such as Portugal, Spain, Algeria, Morocco, France, Italy, and Tunisia, that has the ability to renew its bark indefinitely. Cork is a vegetable plant comprising tissue made up of dead microcells, generally 14-sided polyhedrons, slotting in one against the other, with the intercell space filled with a gaseous mixture, essentially atmospheric air but without the carbon dioxide. It is estimated that 1 cm3 of cork numbers 15 to 40 million hexagonal cells with the thickness of the cellular membranes varying between 1 and 2.5 microns.
The suberose texture is not arranged in a uniform fashion. It is crisscrossed within its thickness by pores or ducts with walls more or less lignified, forming the lenticels. These are filled with powder of a reddish-brown color, rich in tannin. The lenticels are permeable to gases and liquids and they are often invaded by molds and other microorganisms.
The unevenness, both in membrane thickness and in the height and diameter of the cell forming the suberose parenchyma, can affect some of the cork's mechanical and physical properties, namely its compressibility and elasticity. The cork oak being able to keep its physiological process active at all times, the difference in cell size and the thickness of the cellular membrane between cork produced in spring and the succeeding autumn leave discernible rings showing the extent of each year's growth.
The contents of newly formed cells disappear during growth and the subsequent process of suberization of the membranes, on completion of which all communication with the plant's living tissues ceases. The uniqueness of quercus suber is the achieved thickness of cork bark, up to several centimeters, which insulates the tree from heat and loss of moisture and protects it from damage by animals.
In order to harvest the thick cork bark for the first time, the growth cycle takes between 20 and 30 years, depending on location, weather conditions etc. yielding the so-called virgin cork. Afterwards, some 10 years are needed between each harvest of cork boards or reproduction cork in order to gain the necessary length or diameter for some corks. Due to this process, the cork used for the manufacture of bottle closures is a reproduction of cork that is formed again after several barking phases.
The properties of cork derive naturally from the structure and chemical composition of the membranes. Because 89.7% of the tissue consists of gaseous matter, the density of cork is extremely low, about 120 to 200 kg/m3, which makes the cork light and a good insulator. Density differences can be explained by the humidity differences, the age and quality of the cork bark and the cork tree and its growth differences. The cellular membranes are very flexible, rendering the cork both compressible and elastic. Elasticity enables it to rapidly recover to its original dimensions after any deformation. Its chemical composition gives the cork the property of repelling moisture. The walls of the cells are crusted with suberin, a complex mixture of fatty acids and heavy organic alcohols.
The value of cork is further increased by its low conductivity of heat, sound and vibration due to the gaseous elements sealed in tiny, impervious compartments. Cork is also remarkably resistant to wear and has a high friction coefficient, thanks to the honeycomb structure of the suberose surface. Cork does not absorb dust and consequently does not cause allergies nor pose a risk to asthma sufferers. It is fire resistant, recyclable, environmentally friendly and a renewable product.
These advantages have made natural cork the preferred bottle closure for wine storage, particularly for medium and high quality wines where tradition, the wine mystique and the bottle opening ritual with a corkscrew, are a very important, though intangible, aspect of the wine consumption. However, numerous disadvantages of natural cork also exist and derive naturally from the structure and chemical composition of the membranes.
Because cork is a natural product, it is a limited resource. Its limitations become even more obvious with the following facts: the natural growing of cork is geographically limited to the western Mediterranean countries; the world wide annual harvest of cork oak bark is 500,000 tons and can barely be increased, because of climatic and ecological reasons; and ten-year cycles are needed between each harvest of cork boards. In order to meet the rising worldwide cork demand, the pare cycles of cork have been shortened, leading to inferior qualities and constantly rising raw material prices.
The irregularities of the cork's structure due to geographic, climatic and ecological reasons cause many quality variances. This creates a complex categorization of qualities and standards. Through different types of washing processes, various chemical agents are combined in order to decontaminate the cork and to treat the appearance of the cork. High quality corks do not need washing. The cork quality is graded, based on the number of lenticels, horizontal and vertical cracks, their sizes, and other cork specific characteristics. The grading process is a subjective task based on statistically significant populations which is difficult to perform due to its natural origin, since every cork looks, feels, functions and smells different.
Wine market experts estimate that 1% to 5% of all bottled wine is spoiled by cork taint. At least six chemical compounds have been associated with cork taint in wines. Most frequently, 2,4,6-trichloranisole (TCA) is the major culprit responsible for the offensive off-odor and impact on the flavor of the wine. TCA has an extremely low threshold for odor detection. It is detectable at concentrations as low as 1 ppt or 1.0 nanogram per liter.
In most cases, cork taint does not involve the wine-making process. Typically, the tainting chemical is not found in vineyards or in parts of the winery where the wine is produced. After the wine is bottled, the defect shows itself, thus spoiling the wine. It is almost exclusively associated with corks.
Also, there is evidence that once the corks have been treated with chlorine, and are brought into interaction with mold fungus through humidity, chloranisole is created. Other types of wine spoilage are caused by oxidation, hydrogen sulfide, volatile acidity, sulfur dioxide, brettanomyces, and mercaptans.
Another problem commonly found with natural cork is leaking bottles. Typically, the lack of tightness between the cork and the neck of the bottle causes 10% to 20% of bottle leakage. However, the majority of wine leakage is caused by passage of the wine through the cork body. These problems are most often found with lower quality cork material, which is typically porous, too soft, out of round, or out of the predetermined specifications.
In view of the fact that wine spoilage is caused by oxidation of the wine, any gas exchange between ambient conditions and the interior of the wine bottle must be avoided. However, many corks are deformed by the chops or jaws of the bottle corking equipment, which enables air exchange and oxidation to occur. Furthermore, when bottles are stored in an environment where ideal humidity is not maintained, optimum functionality of the cork is not achieved and the cork loses its efficiency as a sealing medium by drying out, becoming brittle and/or losing its mechanical properties. These problems often cause the cork to break when pulled out of the bottle or enable wine spoilage to occur. In addition, natural cork absorbs liquids, depending on its structure and quality. This also results in breakage, while the cork is pulled out of the bottle.
Further problems or deficiencies found with natural cork are the propensity of cork worms to store or lay their eggs on the cork material, enabling the larvae to dig gullies into the cork. Consequently, enlarged apertures or channels are formed in the cork, unknown to the bottler, producing unwanted contamination. In addition to these drawbacks, cork powder and other cork impurities are often able to fall into the wine during the corking process, causing further problems for wine bottlers and unwanted surprises for the wine consumer.
In order to avoid some of the difficulties, bottlers have developed various spray coatings, such as paraffins, silicones and polymer materials, in an attempt to ease the movement of the cork into and out of the bottle, as well as to improve the permeability of the cork and fill imperfections in the cork surface. However, no ideal cork spray coating product has been developed to protect a wine corking member from all of the inherent difficulties or drawbacks of the material.
The vast majority of wine-containing bottles are currently being sold with natural cork stoppers. However, due to the inherent problems existing with natural cork, various other products have been developed to close liquid bearing containers, such as wine bottles. These other closures principally comprise structural synthetic plastics, crown cap metal stoppers, aluminum caps, plastic caps and combinations thereof.
In spite of these prior art efforts, a universally applicable closure has not been developed which satisfies all bottlers and consumer requirements. Particularly, the substantially burdensome requirements imposed upon closure means used in the wine industry have generally been employed as the standard that must be attained by a bottle closure that will be accepted by the industry. As a result of these stringent requirements, these prior art products have been incapable of satisfying the requisite needs of the industry.
In particular, one of the principal difficulties to which any bottle closure is subjected in the wine industry is the manner in which the closure is inserted into the bottle. Typically, the closure is placed in a jaw clamping member positioned above the bottle portal. The clamping member incorporates a plurality of separate and independent jaw members which peripherally surround the closure member and are movable relative to each other to compress the closure member to a diameter substantially less than its original diameter. Once the closure member has been fully compressed, a plunger moves the closure means from the jaws directly into the neck of the bottle, where the closure member is capable of expanding into engagement with the interior diameter of the bottle neck and portal, thereby sealing the bottle and the contents thereof.
In view of the fact that the jaw members must be independent of each other and separately movable in order to enable the closure member to be compressed to the substantially reduced diameter, each jaw member comprises a sharp edge which is brought into direct engagement with the closure member when the closure member is fully compressed. Depending upon the composition of the closure member, score lines are frequently formed on the outer surface of the closure member, which prevents a complete, leak-free seal from being created when the closure member expands into engagement with the bottle neck.
As a result of this sealing system, closure members other than cork have not been accepted by the wine industry, due to their inability to withstand this conventional bottling and sealing method. Furthermore, many cork sealing members also incur damage during the bottling process, resulting in leakage or tainted wine.
Another problem inherent in the wine industry is the requirement that the wine stopper must be capable of withstanding a substantial pressure build up that occurs during the storage of the wine product after it has been bottled and sealed. Due to natural expansion of the wine during hotter months, pressure builds up, imposing a burden upon the bottle stopper that must be resisted without allowing the stopper to be displaced from the bottle. As a result, the bottle stopper employed for wine products must be capable of secure, intimate, frictional engagement with the bottle neck in order to resist any such pressure build up.
A further problem inherent in the wine industry is the requirement that secure, sealed engagement of the stopper with the neck of the bottle must be achieved virtually immediately after the stopper is inserted into the neck of the bottle. During normal wine processing, the stopper is compressed, as detailed above, and inserted into the neck of the bottle to enable the stopper to expand in place and seal the bottle. However, such expansion must occur immediately upon insertion into the bottle since many processors tip the bottle onto its side or neck down after the stopper is inserted into the bottle neck, allowing the bottle to remain stored in this position for extended periods of time. If the stopper is unable to rapidly expand into secure, intimate, frictional contact and engagement with the walls of the neck of the bottle, wine leakage will occur.
A further requirement imposed upon closures or stoppers for wine bottles is the requirement that the closure be removable from the bottle using a reasonable extraction force. Although actual extraction forces extend over a wide range, the generally accepted, conventional extraction force is typically below 100 pounds.
In achieving a commercially viable stopper or closure, a careful balance must be made between secure sealing and providing a reasonable extraction force for removal of the closure from the bottle. Since the requirements for these two characteristics are in direct opposition to each other, a careful balance must be achieved so that the stopper or closure is capable of securely sealing the wine in the bottle, preventing both leakage and gas transmission, while also being removable from the bottle without requiring an excessive extraction force.
Another requirement for commercially viable wine stoppers or closures is the ability for printed material to be placed on the outer surface of the wine closure or stopper in order to allow the wine company to display any desired names, logos, and the like directly on the wine stopper. Depending upon the particular composition of the wine stopper, the requirement for enabling printed material to be placed thereon often imposes difficult conditions and limitations on the construction and functioning of the stopper for its intended purpose.
It has been found with many prior art closures that the process required for enabling the synthetic closure to receive and retain the ink for displaying printed indicia and/or logos also interferes with maintaining a reasonable extraction force for the synthetic closure. In this regard, synthetic closures are required to be specially treated, in order to enable the surface of the synthetic closure to accept the printing ink. Typically, this treatment requires the outer surface of the synthetic closure to be exposed to a high-intensity corona, plasma, or flame.
Although the exposure of the synthetic closure to a high-intensity beam of corona, plasma, or flame typically enables the surface of the closure to receive and retain printing inks, the treatment has been found to have a deleterious effect on the outer surface of the synthetic closure. In this regard, it has been found that extraction forces required to remove the treated synthetic closure from a bottle or container continuously increase with the passage of time. As a result, one of the principal requirements for an effective synthetic closure is not attainable by such prior art products.
Furthermore, printing on the surface of polymeric material has its challenge regarding adhesion, scuff resistance, permanency of the print as well as approval of inks for use in contact with food. Common printing technologies in the field are based on wet ink solutions using either solvent-based, water-based or UV-curable inks. Most any wet ink process requires pre-treating the surface of the polymer in order to increase the bond ability and wet ability of the polymer. This is generally accomplished using corona, flame or plasma treatment process. In the case of UV-curable inks, the exposure to UV light causes the UV initiators in the ink to cross-link and form a more scratch resistant print. It has been documented that using pretreatment processes for preparing the surface of synthetic corks can negatively impact the polymer-glass interface in a way that excessive extraction forces are required to remove the closure from the bottle.
It is highly desirable to accomplish a scratch-resistant print on the surface of the cork to avoid any ink loss or ink transfer to the bottle neck during extraction of the closure. More recently, such developments have been accomplished by using hot stamping and laser marking technologies. Both combine the advantage of not requiring pre-treatment or curing operations. However, in the case of hot stamping the process is governed by heat transfer and is yielding fairly low rates. In the case of laser marking, polyolefin materials require the use of a marking additive to increase absorption and increase marking speed. Those additives have in the past been very costly. In a case of a single-component closure, the additive has to be incorporated into the entire closure, although only marking close to the surface is required.
When UV-curable inks are used, incomplete cross-linking of the ink can cause sensory problems in the wine due to unreacted monomers, in particular acrylates, that can taint the wine. To avoid this problem, the amount of ink has been reduced, so far, resulting in insufficiently dark print.
Most state-of-the-art printing technologies in the field rely on the use of cut corks for the printing process. This is particularly true for injection molded corks, but also applies to extruded corks. As an “offline” process, additional process steps of handling, storing, feeding and waiting are required prior to the printing process. In order to reduce these non-value added times, it is highly desirable to implement a printing process inline to the extrusion process and eliminate most or all non-value added times associated with the printing process.
In a manufacturing process for extruded synthetic closures comprising an inline printing process, several problems have been recognized in the past. Firstly, when the extruded material is cut into pieces with the desired length, it has been realized that the printed indicia are not always at the same position on a finished closure and, eventually, the indicia themselves are cut. Secondly, the cutting machine normally comprises an inline vision system that recognizes a registration mark on the extruded material that triggers the cut. In some cases, however, the indicia printed in addition to the registration mark have competed with the registration mark causing a mistrigger of the cutting machine. Thirdly, the ink is sometimes smeared after being applied to the extruded material or the closure.
Some of these problems might be solved by employing an invisible ink, that is an ink invisible to and/or not detectable by the human eye under normal lighting and/or temperature conditions to trigger the cutting machine. Changing the lighting conditions and/or the temperature and/or irradiating the ink with electromagnetic radiation of a certain frequency outside the visible spectrum such as x-ray, ultraviolet, infrared or radio frequency and/or applying a chemical reagent can visualize this invisible ink and/or make the ink detectable.
U.S. Pat. No. 3,589,280 describes an apparatus for printing of invisible indicia using ultraviolet ink on metal caps or containers. U.S. Pat. No. 7,394,383 describes containers for pharmaceutical products comprising a cap with indicia that may be visible or invisible when viewed under normal lighting conditions. The indicia are printed onto a film which is subsequently embedded into a polymeric material. US 2003/0129283 describes indicia printed onto metallic containers and/or closures which are visible under ultraviolet light. WO 2014/007807 describes printing invisible indicia both onto the top of a cork in a wine bottle and onto the glass of the bottle. US 2009/0130350 describes an inline printing process incorporated into a manufacturing process for synthetic closures by extrusion. So far, invisible ink has not been applied onto synthetic polymer closures directly. Additionally, invisible ink has not been applied to surfaces of a closure that can at least temporarily come into contact with the content of the container. This can cause problems as the ink may spoil the content of the container. Furthermore, in inline printing systems for closures prepared by continuous extrusion, irregularities in the cutting process have been observed. Another problem in this regard is smearing of the printed indicia during and/or after the manufacturing process.
In addition to the printing process, the closure requires a surface lubrication to enable cork insertion and extraction into the bottle. It is of great interest to also include this process into the extrusion process in order to obtain a finished product at the end of the extrusion line that can readily be packed and shipped. Lubricating agents used in the industry include silicone oils and paraffin. Printing after lubricating the surface is virtually impossible for most wet-ink and hot stamping processes. In the case of laser marking, a print after coating is obtainable. However, the use of additives and the capital cost of the equipment is cost prohibitive to the manufacturing process. In the case of producing a single-component closure, surface coating after inline printing could take the shape of inline spray-coating the surface of the extrusion rod after printing prior to cutting the corks. In the case of a multi-component closure (core with an outer layer) and crosshead extruding the product, it is possible to print after extruding the core and incorporating the lubrication function into the outer layer (e.g. incorporation of mineral oils or silicone oils into the formulation of the outer layer). Lubrication of the outer layer can be effected by adding a suitable additive or lubrication polymer (e.g. Teflon) into the formulation of the outer layer.
Another problem associated with the shipping of corks is the inefficient packing properties of the closures. Due to their substantially cylindrical shape with a low aspect ratio, packing of closures yields many voids when boxed resulting in unnecessarily large volume requirements.
It is an object of the present disclosure to provide a synthetic closure or stopper with indicia imprinted that are invisible under normal lighting and/or temperature conditions. The printed indicia should preferably not be smeared in the manufacturing process.
Another object of the present disclosure is to prevent or reduce irregularities in the cutting process.
Furthermore, the synthetic closure or stopper comprising artwork should preferably not taint wine.
Another object of the present disclosure is to provide a rod-shaped intermediate product that can be efficiently packed and cut into a plurality of closures or stoppers.
Another object of the present disclosure is to provide a synthetic closure or stopper having the characteristic features described above which is capable of providing a wide variety of alternate surface textures or treatments or visual appearances.
Other and more specific objects will in part be obvious and will in part appear hereinafter.